ACTN3 R577X Research Articles

ACTN3 R577X Gene Variant Is Associated With Muscle-Related Phenotypes in Elite Chinese Sprint/Power Athletes.

Yang, R, Shen, X, Wang, Y, Voisin, S, Cai, G, Fu, Y, Xu, W, Eynon, N, Bishop, DJ, and Yan, X. ACTN3 R577X gene variant is associated with muscle-related phenotypes in elite Chinese sprint/power athletes. J Strength Cond Res 31(4): 1107-1115, 2017-The ACTN3 R577X polymorphism (rs1815739) has been shown to influence athletic performance. The aim of this study was to investigate the prevalence of this polymorphism in elite Chinese track and field athletes, and to explore its effects on athletes' level of competition and lower-extremity power. We compared the ACTN3 R577X genotypes and allele frequencies in 59 elite sprint/power athletes, 44 elite endurance athletes, and 50 healthy controls from Chinese Han origin. We then subcategorized the athletes into international level and national level and investigated the effects of ACTN3 genotype on lower-extremity power. Genotype distribution of the sprint/power athletes was significantly different from endurance athletes (p = 0.001) and controls (p < 0.001). The frequency of the RR genotype was significantly higher in international-level than that in the national-level sprint/power athletes (p = 0.004), with no international-level sprint/power athletes with XX genotype. The best standing long jump and standing vertical jump results of sprint/power athletes were better in the RR than those in the RX + XX genotypes (p = 0.004 and p = 0.001, respectively). In conclusion, the ACTN3 R577X polymorphism influences the level of competition and lower-extremity power of elite Chinese sprint/power athletes. Including relevant phenotypes such as muscle performance in future studies is important to further understand the effects of gene variants on elite athletic performance.

Association between ACTN3 R577X Polymorphism and Trunk Flexibility in 2 Different Cohorts.

α-Actinin-3 (ACTN3) R577X polymorphism is associated with muscular strength and power. This study was performed to investigate the association between ACTN3 R577X polymorphisms and flexibility as another component of fitness in 2 cohorts. Cohort 1 consisted of 208 men and 568 women (ages 23-88), while Cohort 2 consisted of 529 men and 728 women (ages 23-87). All participants were recruited from the Tokyo metropolitan area and underwent a battery of tests to assess their grip strength and sit-and-reach flexibility. Genotyping results were analyzed for ACTN3 (rs1815739) polymorphism using the TaqMan approach. In Cohort 1, sit-and-reach in the RR genotype (35.3±0.7 cm) was significantly lower than those in the RX and XX genotypes (37.2±0.3 cm) even after adjusting for sex, age, and exercise habit as covariates (P<0.01). In Cohort 2, sit-and-reach tended to be lower in RR (38.1±0.6 cm) than in RX and XX (39.1±0.3 cm), but the differences were not significant (P=0.114). Analysis in pooled subjects indicated that RR was associated with significantly lower flexibility than RX and XX (P=0.009). The RR genotype of ACTN3 R577X in the general Japanese population showed lower flexibility compared to the RX and XX genotypes.

Exploring the relationship between \u03b1-actinin-3 deficiency and obesity in mice and humans

Obesity is a worldwide health crisis, and the identification of genetic modifiers of weight gain is crucial in understanding this complex disorder. A common null polymorphism in the fast fiber-specific gene ACTN3 (R577X) is known to influence skeletal muscle function and metabolism. α-Actinin-3 deficiency occurs in an estimated 1.5 billion people worldwide, and results in reduced muscle strength and a shift towards a more efficient oxidative metabolism. The X-allele has undergone strong positive selection during recent human evolution, and in this study, we sought to determine whether ACTN3 genotype influences weight gain and obesity in mice and humans. An Actn3 KO mouse has been generated on two genetic backgrounds (129X1/SvJ and C57BL/6J) and fed a high-fat diet (HFD, 45% calories from fat). Anthropomorphic features (including body weight) were examined and show that Actn3 KO 129X1/SvJ mice gained less weight compared to WT. In addition, six independent human cohorts were genotyped for ACTN3 R577X (Rs1815739) and body mass index (BMI), waist-to-hip ratio-adjusted BMI (WHRadjBMI) and obesity-related traits were assessed. In humans, ACTN3 genotype alone does not contribute to alterations in BMI or obesity.

Influence of Polymorphisms in the Gene ACTN3 R577X in Power Athletes

Influence of Polymorphisms in the Gene ACTN3 R577X in Power Athletes

Evidence for ACTN3 as a genetic modifier of Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is characterized by muscle degeneration and progressive weakness. There is considerable inter-patient variability in disease onset and progression, which can confound the results of clinical trials. Here we show that a common null polymorphism (R577X) in ACTN3 results in significantly reduced muscle strength and a longer 10 m walk test time in young, ambulant patients with DMD; both of which are primary outcome measures in clinical trials. We have developed a double knockout mouse model, which also shows reduced muscle strength, but is protected from stretch-induced eccentric damage with age. This suggests that α-actinin-3 deficiency reduces muscle performance at baseline, but ameliorates the progression of dystrophic pathology. Mechanistically, we show that α-actinin-3 deficiency triggers an increase in oxidative muscle metabolism through activation of calcineurin, which likely confers the protective effect. Our studies suggest that ACTN3 R577X genotype is a modifier of clinical phenotype in DMD patients.

The influence of genetic polymorphisms on performance and cardiac and hemodynamic parameters among Brazilian soccer players.

This study investigated whether ACTN3 R577X, AMPD1 C34T, I/D ACE, and M235T AGT polymorphisms can affect performance tests such as jumping, sprinting, and endurance in 220 young male athletes from professional minor league soccer team from São Paulo Futebol Clube, Brazil. I/D ACE and M235T AGT polymorphisms were also analyzed according to cardiac and hemodynamic parameters. Athletes were grouped or not by age. DNA from saliva and Taqman assays were used for genotyping 220 athletes and the results were associated with performance tests. Ventricle mass, ventricle end-diastolic diameter, end-diastolic volume, and ejection fraction were assessed by echocardiogram. Arterial pressure, heart rate, and oximetry were assessed by a cardioscope. The main results of this study were that athletes who carried RR/RX (ACTN3) and DD (ACE) genotypes presented better performance during jump and sprint tests. On the other hand, athletes with ID/II genotype presented better results during endurance test, while AGT genotypes did not seem to favor the athletes during the evaluated physical tests. CC genotype (AMPD1) only favored the athletes during 10-m sprint test. Although there are environmental interactions influencing performance, the present results suggest that RR/RX ACTN3 and ACE DD genotypes may benefit athletes in activities that require strength and speed, while II ACE genotype may benefit athletes in endurance activities. This information could help coaches to plan the training session to improve the athletes' performance.

Greater muscle damage in athletes with ACTN3 R577X (RS1815739) gene polymorphism after an ultra-endurance race: a pilot study.

In this study, we aimed to investigate the influence of ACTN3 R577X gene polymorphism on muscle damage responses in athletes competing in an ultra-endurance race. Twenty moderate to well-trained ultra-runners who had entered in an official 37.1 km adventure race (22.1 km mountain biking, 10.9 km trekking, 4.1 km water trekking, 30 m rope course, and orienteering) volunteered for the study. Blood samples were collected for genotyping and analysis of muscle protein levels before and after the race. Percentage changes (pre- to post-race) of serum myoglobin [XX = 5,377% vs. RX/RR = 1,666%; P = 0.005, effect size (ES) = 1.73], creatine kinase (XX = 836.5% vs. RX/RR = 455%; P = 0.04, ES = 1.29), lactate dehydrogenase (XX = 82% vs. RX/RR = 65%; P = 0.002, ES = 1.61), and aspartate aminotransferase (XX = 148% vs. RX/RR = 75%; P = 0.02, ES = 1.77) were significantly greater for XX than RX/RR genotypes. ES analysis confirmed a large magnitude of muscle damage in XX genotype ultra-runners. Therefore, athletes with the ACTN3 577XX genotype experienced more muscle damage after an adventure race. This suggests that ultra-runners with alpha-actinin-3 deficiency may be more susceptible to rhabdomyolysis and associated health complications during ultra-endurance competitions.

Prevalence of ACTN3 R577X Polymorphism in Chinese University Students

Prevalence of ACTN3 R577X Polymorphism in Chinese University Students

ACTN3 X-allele carriers had greater levels of muscle damage during a half-ironman.

Alpha-actinin-3, encoded by the ACTN3 gene, is an actin-binding protein with an important role in myofibril contraction and muscle force output. In humans, there is a relatively common deficiency of the α-actinin-3 due to homozygosity in a polymorphism of the ACTN3 gene (R577X, rs1815739), that has been related to decreased resistance to strain during voluntary muscle contractions. The purpose of this study was to investigate the influence of the ACTN3 genotype on the level of exercise-induced muscle damage attained by 23 experienced triathletes during an official half-ironman competition. Before and after the race, a sample of venous blood was obtained and jump height was measured during a countermovement jump. The changes in serum creatine kinase (CK-MM isoform) were measured in the blood samples and muscle pain was measured with a visual analogue scale (0-10cm). Data from RX heterozygotes and XX mutant homozygotes were grouped as X-allele carriers (n=13) and compared to RR homozygotes (n=10). Race time was very similar between groups (313±31 vs. 313±25min; P=0.45); however, pre-to-post-competition reduction in jump height was greater in X-allele carriers than RR homozygotes (-18.4±11.4 vs. -8.2±6.9%; P=0.04). At the end of the race, X-allele carriers presented higher serum CK-MM concentrations (682±144 vs. 472±269U/L; P=0.03), and there was also a tendency for higher self-reported values of lower limb muscle pain (7.7±1.1 vs. 6.3±2.3cm; P=0.06). X-allele triathletes in the ACTN3 R577X polymorphism presented greater signs of exercise-induced muscle damage during a half-ironman race than RR homozygotes.

ACTN3 R577X genotype and performance of elite middle-long distance swimmers in China.

The ACTN3 gene is one of the genes that have a potential influence on physical performance. Studies have shown that the 577R genotype of ACTN3 is more prevalent in sprint athletes, while the 577X genotype is more prevalent in endurance athletes. In swimming, both power and endurance related phenotypes are equally needed for swimmers to excel at the elite level. Therefore, the ACTN3 R577X polymorphism may become a genetic marker for swimmers. The study aimed to examine the association of the ACTN3 R577X genotype with the performance of elite middle-long distance (MLD) swimmers. The distributions of the ACTN3 R577X (rs1815739) genotype and allele were examined in a general population (206) and a group of elite MLD swimmers (160) in China by using PCR-RFLP and TOF. Compared with the general population, the elite MLD swimmers, especially the females, had a higher frequency of the RR genotype. The swimmers had a higher frequency of the R allele than the general population. However, the difference was not statistically significant. After being stratified by performance, the difference of the R allele frequency between the international master athletes and the general population was statistically significant. The elite MLD swimmers had a higher frequency of the RR genotype than the RX+XX genotype compared with the general population. The ACTN3 R577X polymorphism was associated with the performance of elite MLD swimmers in China. The SNP R577X could be used as a biomarker for selecting elite MLD swimmers in China.

Advances in Exercise, Fitness, and Performance Genomics in 2015.

This review of the exercise genomics literature encompasses the highest-quality articles published in 2015 across seven broad topics: physical activity behavior, muscular strength and power, cardiorespiratory fitness and endurance performance, body weight and adiposity, insulin and glucose metabolism, lipid and lipoprotein metabolism, and hemodynamic traits. One study used a quantitative trait locus for wheel running in mice to identify single nucleotide polymorphisms (SNPs) in humans associated with physical activity levels. Two studies examined the association of candidate gene ACTN3 R577X genotype on muscular performance. Several studies examined gene-physical activity interactions on cardiometabolic traits. One study showed that physical inactivity exacerbated the body mass index (BMI)-increasing effect of an FTO SNP but only in individuals of European ancestry, whereas another showed that high-density lipoprotein cholesterol (HDL-C) SNPs from genome-wide association studies exerted a smaller effect in active individuals. Increased levels of moderate-to-vigorous-intensity physical activity were associated with higher Matsuda insulin sensitivity index in PPARG Ala12 carriers but not Pro12 homozygotes. One study combined genome-wide and transcriptome-wide profiling to identify genes and SNPs associated with the response of triglycerides (TG) to exercise training. The genome-wide association study results showed that four SNPs accounted for all of the heritability of △TG, whereas the baseline expression of 11 genes predicted 27% of △TG. A composite SNP score based on the top eight SNPs derived from the genomic and transcriptomic analyses was the strongest predictor of ΔTG, explaining 14% of the variance. The review concludes with a discussion of a conceptual framework defining some of the critical conditions for exercise genomics studies and highlights the importance of the recently launched National Institutes of Health Common Fund program titled "Molecular Transducers of Physical Activity in Humans."

Lack of replication of associations between multiple genetic polymorphisms and endurance athlete status in Japanese population.

The aim of this study was to examine a polygenic profile related to endurance performance, based on current knowledge, in the Japanese population. We analyzed 21 genetic polymorphisms that have been reported to be associated with endurance performance and its related phenotypes in 175 endurance runners (60 international‐, 94 national‐, and 21 regional‐level) and 649 controls in the Japanese population. Then, we calculated the total genotype score (TGS) (maximum value of 100 for the theoretically optimum polygenic score) for endurance performance. There was no association between the TGS and endurance athlete status (Control: 49.0 ± 7.6, Regional: 47.3 ± 7.6, National: 49.1 ± 5.7, and International: 48.2 ± 7.0, P = 0.626). These results suggested that TGSs based on the 21 previously published endurance performance‐associated polymorphisms do not influence endurance running performance in the Japanese population. Nevertheless, some marginal tendencies have to be noted: the frequencies of the ACTN3 R577X rs1815739 RR+RX genotype and the GNB3 rs5443 CC+CT genotype were higher in international athletes than in controls (85% vs. 73.6%, P = 0.042 and 90% vs. 76%, P = 0.007, respectively), but not significantly different after Bonferroni correction.

Literature Review of Turkish Sportsmen in Terms of ACTN3 R577X Polymorphism

Genlerin atletik performans uzerine etkisi kabul edilmekle birlikte etkinin boyutlari halen arastirma konusudur. Gunumuze kadar atletik performansa etki ettigi dusunulen genetik golgeler ve futbol, basketbol, judo, gures gibi farkli spor branslarina ait sporcular uzerinde bircok calisma gerceklestirilmistir. Ancak Turk sporcular icin bu calismalar literatur ile karsilastirildiginda daha az sayidadir. Bu derlemede gunumuze kadar gerceklestirilen Turk sporcularin alfa- aktinin-3 geni (ACTN3) R577X polimorfizm sonuclarini, detayli bir literatur taramasi sonucunda bir araya getirmeyi amacladik. Ilgili literatur taramasinin ardindan aralarinda futbol, basketbol, gures gibi farkli spor dallarindan toplam 518 sporcunun analiz sonuclarina ulastik. Bu sporcularin 234’unun (%45) RR, 207’sinin (%40) RX ve 77’sinin (%15) XX genotipinde oldugu gorulmektedir. Sporculardaki sprinter ve guc alleli olan R alleli 665 (%64), dayaniklilik alleli olan X alleli ise 371 (%36) olarak bulunmustur. Elde ettigimiz verilere gore RR + RX genotipleri ve R alleli, XX genotipi ve X alleline gore sayi ve yuzde bazinda daha yuksektir. Gerceklestirilen bu literatur taramasi, Turk sporcularda ACTN3 R577X polimorfizmi dagilimlari bakimindan gerceklestirilen ilk calisma olup Turk sporcular icin iyi bir veri olacagini, yapilacak sonraki calismalar icin de iyi bir kaynak olacagini dusunmekteyiz.

Actn3 R577x Polymorphism Is Associated With Trunk Flexibility In Two Different Cohorts

Actn3 R577x Polymorphism Is Associated With Trunk Flexibility In Two Different Cohorts

Progressive Resistance Training Modulates the Expression of ACTN2 and ACTN3 Genes and Proteins in the Skeletal Muscles

Purpose: Mammalian skeletal muscle has the two isoforms of actin binding protein, α-Actinin-2 and α-Actinin-3, which are located in the skeletal muscle Z-line where they cross-link the actin thin filaments. There is a common stop codon polymorphism R577X in the ACTN3 gene. Several association studies have demonstrated that the ACTN3 R577X genotype influences athletic performance. The response of α-Actinins to resistance exercise training is little understood. Methods: Female Sprague-Dawley rats were assigned to control (C; n = 10) and resistance training (T; n = 12) groups. Training consisted of climbing a ladder carrying a load suspended from the tail. After training, fast (Flexor halluces longus, FHL) and slow (Soleus) hind limb muscles from each group was examine to study the effect of resistance training on muscle mass. Gene expression and protein levels of both Actn3, Actn2 were examined. Results: The resistance trained group had a significantly greater absolute muscle mass in FHL (P=0.011). We also found that Actn3 and Actn2 gene expression levels increased significantly in FHL and Soleus muscles by mean factors of 2.16, and 2.91, respectively. α-Actinin-2 protein expression increased significantly in training group (P=0.025) while, α-actinin-3 protein expression remained similar in training & control groups (P=0.130). The most important finding of this study showed that both α-actinin-3 and α-actinin-2 mRNA levels were up-regulated after 8wk of resistance training (P≤0.05). Conclusion: Our results provide a new insight into the impact of progressive resistance training and evaluating the role of α-actinins responsiveness.

ACTN3 R577X and ACE I/D gene variants influence performance in elite sprinters: a multi-cohort study.

BackgroundTo date, studies investigating the association between ACTN3 R577X and ACE I/D gene variants and elite sprint/power performance have been limited by small cohorts from mixed sport disciplines, without quantitative measures of performance. Aim: To examine the association between these variants and sprint time in elite athletes.MethodsWe collected a total of 555 best personal 100-, 200-, and 400-m times of 346 elite sprinters in a large cohort of elite Caucasian or African origin sprinters from 10 different countries. Sprinters were genotyped for ACTN3 R577X and ACE ID variants.ResultsOn average, male Caucasian sprinters with the ACTN3 577RR or the ACE DD genotype had faster best 200-m sprint time than their 577XX (21.19 ± 0.53 s vs. 21.86 ± 0.54 s, p = 0.016) and ACE II (21.33 ± 0.56 vs. 21.93 ± 0.67 sec, p = 0.004) counterparts and only one case of ACE II, and no cases of ACTN3 577XX, had a faster 200-m time than the 2012 London Olympics qualifying (vs. 12 qualified sprinters with 577RR or 577RX genotype). Caucasian sprinters with the ACE DD genotype had faster best 400-m sprint time than their ACE II counterparts (46.94 ± 1.19 s vs. 48.50 ± 1.07 s, p = 0.003). Using genetic models we found that the ACTN3 577R allele and ACE D allele dominant model account for 0.92 % and 1.48 % of sprint time variance, respectively.ConclusionsDespite sprint performance relying on many gene variants and environment, the % sprint time variance explained by ACE and ACTN3 is substantial at the elite level and might be the difference between a world record and only making the final.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2462-3) contains supplementary material, which is available to authorized users.

The ACTN3 R577X polymorphism affects the lipid profile and the prognosis of nutritional intervention in HIV-positive patients

The hypothesis of the present study is that the polymorphisms in the APOC3, CEPT, ACE, and ACTN3 genes can affect the outcome of nutritional intervention and the plasma lipid profile of HIV+ patients. To test the hypothesis, genetic material was collected from buccal cells, and serum was collected for biochemical analysis. Sixty-five patients were analyzed. The incorporation of protease inhibitor (PI) was more frequent in women (77% vs 33% in men). Nutritional intervention improved anthropometric parameters independent of the genotype. Patients with the RR genotype for the ACTN3 R577X polymorphism had lower glycemia (RR = 95.4 ± 6.5 mg/dL, RX = 102.6 ± 10.6 mg/dL, XX = 110.1 ± 16.3 mg/dL; P = .03) and a greater reduction in low-density lipoproteins (LDL) after intervention (LDL: RR = −23.7 ± 15.8 mg/dL, RX = 1.32 ± 5.13 mg/dL, XX = 30.21 ± 24.4 mg/dL; P = .01). Patients using PI had a negative response to dietary intervention regarding the levels of high-density lipoprotein (−2.4 ± 1.70 with PI, 2.56 ± 1.60 mg/dL without PI; P = .02), very low density lipoprotein (0.84 ± 2.73 with IP, −5.46 ± 3.37 mg/dL without PI; P = .03), and triglycerides (1.79 ± 13.22 with PI, −34.00 ± 17.67 mg/dL without PI; P = .052). This response was also independent of the genotype (P > 0.05) and suggested the need for oral lipid-lowering drugs in all HIV+ patients using PI. Our results indicate that the ACTN3 R577X polymorphism is a good predictor of both the lipid profile and the prognosis of nutritional intervention in reducing LDL in HIV+ patients.

Association of ACTN3 R577X but not ACE I/D gene variants with elite rugby union player status and playing position.

We aimed to quantify the ACE I/D and ACTN3 R577X (rs1815739) genetic variants in elite rugby athletes (rugby union and league) and compare genotype frequencies to controls and between playing positions. The rugby athlete cohort consisted of 507 Caucasian men, including 431 rugby union athletes that for some analyses were divided into backs and forwards and into specific positional groups: front five, back row, half backs, centers, and back three. Controls were 710 Caucasian men and women. Real-time PCR of genomic DNA was used to determine genotypes using TaqMan probes and groups were compared using χ2 and odds ratio (OR) statistics. Correction of P values for multiple comparisons was according to Benjamini-Hochberg. There was no difference in ACE I/D genotype between groups. ACTN3 XX genotype tended to be underrepresented in rugby union backs (15.7%) compared with forwards (24.8%, P = 0.06). Interestingly, the 69 back three players (wings and full backs) in rugby union included only six XX genotype individuals (8.7%), with the R allele more common in the back three (68.8%) than controls (58.0%; χ2 = 6.672, P = 0.04; OR = 1.60) and forwards (47.5%; χ2 = 11.768, P = 0.01; OR = 2.00). Association of ACTN3 R577X with playing position in elite rugby union athletes suggests inherited fatigue resistance is more prevalent in forwards, while inherited sprint ability is more prevalent in backs, especially wings and full backs. These results also demonstrate the advantage of focusing genetic studies on a large cohort within a single sport, especially when intrasport positional differences exist, instead of combining several sports with varied demands and athlete characteristics.

Genetic polymorphisms in alpha-actinin 3 and ­adrenoceptor beta genes in Austrian elite athletes and healthy controls

Background: During the last years many studies were conducted to investigate the contribution of various genetic variants to endurance and sprint/power performance of elite athletes. Data on team sport athletes are missing to a large extent. Therefore, the aim of the study was to investigate the frequency of selected polymorphisms on elite athlete status in Austrian team sport (handball, soccer), endurance and power athletes as well as in healthy control subjects. Methods: Genotype and allele frequencies of ACTN3 R577X (rs1815739), ADRB1 Ser49Gly (rs1801252), ADRB2 Arg16Gly (rs1042713), ADRB2 Gln27Glu (rs1042714) and the ADRB3 Trp64Arg (rs4994) polymorphisms were determined in 56 Austrian sprint/power athletes, 86 endurance athletes, 143 team sport athletes and 216 healthy non-athletic controls. Genomic DNA was extracted from saliva and genotyping was performed by real time polymerase chain reaction using a standard protocol. Results: Handball and soccer players had a higher frequency of the ACTN3 RR genotype and a lower frequency of RX + XX genotypes than the control group. Furthermore, the frequency of athletes being homozygous for the ADRB1 Ser49Ser genotype was significantly higher in team sport athletes in comparison to those competing in power/sprint sports. We did not detect any other differences in genotype distributions between the study groups. Conclusion: This study provides some evidence that the ACTN3 R577X and the ADRB1 Ser49Gly polymorphisms are associated with team sport performance. Larger prospective studies focusing on the genetic influence of performance development are required for confirmation of these findings.

Genetic association between ACTN3 polymorphism and risk of non-acute ankle sprain.

In this study, we investigated the association between ACTN3 R577X polymorphism and non-acute ankle sprain by measuring the allele frequency and genotype distribution of ACTN3 in a Chinese Han population. We recruited 100 patients with non-acute ankle sprain and 100 healthy controls with no history of ankle injuries. Mass spectrometric analysis of single nucleotide polymorphism was used to analyze the genotype and allele frequencies of ACTN3. Results showed that the genotype frequency of RR in patients was 12.0%, which was significantly lower than that of the controls (24.0%) (OR = 1.7; 95%CI = 1.5-2.7; P = 0.001). The frequency distribution of the R allele in patients and controls were 68.5 and 56.7%, respectively (P = 0.002). Moreover, frequency of the RR genotype exhibited a downward linear trend with increased incidences of ankle sprain. Our results suggest that ACTN3 R577X polymorphism is associated with non-acute ankle sprain in the Chinese Han population.